Autopositive reproduction material



United States Patent Office 3,526,507 Patented Sept. 1, 1970 US. Cl. 96101 9 Claims ABSTRACT OF THE DISCLOSURE An autopositive photographic material having substantially improved resistance to white-light deterioration has a light-sensitive emulsion comprising a silver halide with fogging nuclei, a desensitizer compound such as Pinachryptol Yellow, and a 4-hydroxy-tetra-azaindene.

This invention relates to an autopositive light-sensitive silver halide photographic material which is capable of yielding a positive image through a single pass of light exposure and development by utilization of Herschel effect.

As is Well known, an autopositive light-sensitive photographic material of that type is intended to obtain a direct positive image through reversal development using Herschel eflect, and it comprises a light-sensitive silver halide layer previously provided with fogging nuclei and containing a desensitizer such as Pinachryptol Yellow, Pinachryptol Green, Phenosafranine, etc., to have accelerated reversing speed of Herschel effect. One of the characteristics of the above-referred autopositive lightsensitive photographic material is that it can be safely handled under room light, e.g., tungsten lamp. However, the autopositive light-sensitive material which has been known heretofore suffers from such detrimental drawback I that the fogging nuclei previously imparted to the silver halide causes a degradation phenomenon due to the action of yellow (with a wavelength of more than 500 mu) when said material is stored under a white light source for a long period or exposed to white light at the neighborhood of its source, so that an image with decreased density is yielded after development.

In a certain prior art literature (Japanese patent publication No. 22,326/ 1963), incorporation of a coloring matter capable of absorbing yellow or other longer wave length light into the top coating or emulsion layer of a light-sensitive photographic element has been proposed in order to prevent degradation of the fogging nuclei. Typical coloring matter may be a blue color dye. Because of its being blue in color, however, the dye stains the coated surface bluish so that it may disadvantageously absorb light of long wave length in Herschel effect, with the possible decrease in the efficiency of exposure.

Now, according to the present invention, an autopositive. light-sensitive photographic material which has good safety against white light exposure can be obtained by using, together with a known desensitizer such as Pinachryptol Yellow, Pinachryptol Green, Phenosafranine, etc., a tetra-aza-indene compound of the general formula wherein R is hydrogen atom, alkyl, aralkyl, aralkyl or aryl radical, cyclic hydrocarbon residue or heterocyclic ring residue; R is hydrogen atom, alkyl, aralkyl or aryl radical; and R is hydrogen atom, alkyl or carboxyl radical or halogen atom; and R and R together may form an atomic grouping which is one member constituting a S-membered or 6-membered cyclic hydrocarbonic or heterocyclic ring.

Tetra-aza-indene compounds which are suitable in the present invention generally are produced by reacting a 6-ketoester with a 3-amino-1,2,4-triazole at an equimolar proportion at an elevated temperature. Typical compounds are listed below:

III

Tetra-aza-indene compounds of the present invention are not detrimental to the reversing action due to Herschel effect accelerated by use of a desensitizer. Thus, there are no adverse effects in the photographic properties of the resulting elements and no change in color of papers or the like supports. Tetra-aza-indene compounds of the specified general formula, and the desensitizers (Pinachryptol Yellow, Pinachryptol Green, Safranine, etc.) should be used in amount of 0.05-5 g. and 0.04-4 g., respectively, per mole of the silver halide. These components are dissolved in a solvent (water or lower alcohol or the 3 mixture of both) and then the resulting solution is added to the emulsion at an appropriate stage after its ripening and before its coating.

The following examples will show the present invention in detail.

EXAMPLE 1 To one kilogram of a pure silver chloride emulsion containing 40 g. of silver nitrate, 30 cc. of 6% aqueous sodium metaborate solution is added to adjust the emulsion pH at 8.5. T hereto, 7 cc. of 3% aqueous formalin solution is added and the resulting mixture is heated at 40 C. for 30 minutes thereby to form fogging nuclei. To this mixture is added 10% aqueous citric acid solution to have a pH of 6.0. 60 cc. of an aqueous solution of 0.1% Pinachryptol Yellow and 80 cc. of an aqueous solution of 0.1% tetraza-indene compound (III) are also added. The resulting total emulsion is coated on a photographic paper. The resulted product is useful as an autopositive light-sensitive material. For control, another pho- (VI) in aqueous methanol (1:1) are added to the emulsion but for non-inclusion of the compound (III) is prepared and coated on similar photographic paper.

The two coated photographic papers are positioned at a distance of l m. from 40-watt tungsten lamp for a predetermined period and then exposed imagewise in the usual manner to yellow light. After exposure to the tungsten lamp for about one minute, the photographic paper prepared as control gives a practically useless positive. On the contrary, the photographic material of the present invention can be exposed to the tungsten lamp for 9 minutes and still give a satisfactory positive. No loss of Herschel effect sensitivity upon exposure to yellow light is observed in the material of the present invention.

EXAMPLE 2 To one kilogram of a silver chloroiodide emulsion containing 40 g. of silver nitrate, 25 cc. of aqueous sodium carbonate solution are added to make the emulsion at pH 7. 10 cc. of 3% aqueous formalin are added and the resulting mixture is ripened at 55 C. for 60 minutes thereby to form fogging nuclei. 10% aqueous citric acid solution is added to the mixture to adjust its pH to 6.0. 100 cc. of an aqueous solution of 0.1% Pinachryptol Yellow and 40 cc. of a solution of 0.2% the compound (VI) in agueous methanol (1:1) are added to the emulsion which is then coated on a photographic paper. For comparison, another photographic emulsion is prepared in the same way but excepting addition of the compound (VI) and it is coated on similar photographic paper.

The coated two photographic papers are exposed for a determined period at a distance of 1 m. from a 40-watt tungsten lamp and 2 m. from a daylight fluorescent lamp, before they are exposed imagewise to yellow light. The result shows that the photographic paper used as control can be safe only for one minute under the tungsten lamp and for 45 seconds under the fluorescent lamp, while the photographic paper prepared according to the invention can give a satisfactory positive even after remaining for 10 minutes and 7 minutes respectively under the tungsten lamp and the fluorescent lamp.

The above examples have been presented for the purpose of illustration and should not be taken to limit the scope of the present invention. It will be apparent that the described examples are capable of many variations and modifications which are likewise to be included within the scope of the present invention as set forth in the appended claims.

What is claimed is:

1. Autopositive reproduction material comprising:

(a) a support; and

(b) an autopositive light-sensitive emulsion layer, said layer comprising:

(1) a light-sensitive silver halide having foggingnuclel;

(2) a desensitizer compound; and

(3) a tetra-aza-indene compound of the general formula:

wherein R is hydrogen or an alkyl, aralkyl, or aryl group; or a cyclic or heterocyclic residue; and wherein R and R are selected from one of: Group A, wherein R is hydrogen or an alkyl, aralkyl or aryl group; and R is hydrogen, halogen or an alkyl or carboxyl group; or Group B, wherein R and R together form a 5- or 6- membered cyclic or heterocyclic ring.

2. Material according to claim 1 wherein said desensitizer compound is selected from the group consisting of Pinachryptol Yellow, Pinachryptol Green, and Safranine.

3. Material according to claim 2 wherein said tetraaza-indene is the compound of Formula I.

4. Material according to claim 2 wherein said tetraaza-indene is the compound of Formula II.

5. Material according to claim 2 wherein said tetra-azaindene is the compound of Formula III.

6. Material according to claim 2 wherein said tetra-azaindene is the compound of Formula IV.

7. Material according to claim 2 wherein said tetra-azaindene is the compound of Formula V.

8. Material according to claim 2 wherein said tetra-azaindene is the compound of Formula VI.

9. Material according to claim 2 wherein said tetra-azaindene is the compound of Formula VII.

References Cited UNITED STATES PATENTS 2,444,605 7/ 1948 Heimbach et al 96109 2,444,607 7/1948 Heimbach 96109 2,716,062 8/1955 Carroll et a1 96108 3,178,282 4/ 1965 Luckey et al 9668 3,403,025 9/1968 Rees et al 96101 3,178,282 4/1965 Luckey et a1 9668 3,202,512 8/ 1965 Williams 96107 NORMAN G. TORCHIN, Primary Examiner A. T. SURO PICO, Assistant Examiner US. Cl. X.R. 9645.2

T323530 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,526,507 Dated 1 September 1970 Inyentor(s) Hidehiko Ishikawa, Shnzo Ozaki and Shut Sato It. is certified that error appears in the above-identified patent and that. said Letters Patent are hereby corrected as shown below:

Column 2, Formula (VII) should read:

Column 3, line 21 should read:

graphic emulsion which is the same as the above emulnova 19D -W11 mm x BOHUYIM,

Ofim Oomaaiom r a: J 

